"In this article, I show at the transistor and silicon level. I've discussed the mathematics of the 6502 overflow flag earlier and thought it would be interesting to look at the actual chip-level implementation. Even though the overflow flag is a slightly obscure feature, its circuit is simple enough that it can be explained at the silicon level."

A lot of optimizations can be done with the CPU flags. The trouble is that high level programming languages don't expose them, I'm looking at you C. The C language for it's part assumes the flags don't exist so that it doesn't have to emulate them on architectures which don't have them.

IMHO the lack of overflow flags is a deficiency of most high level languages.

Another flag we don't see much of is the parity flag, but I've found a very interesting way to use parity bits to optimize multi-word multiplication algorithms. An efficient population count function would do the trick too since the least significant bit represents parity. Even though C is thought to be the best low level language, there still exists a gap between it and assembly language.